P. Le Coustumer

Characterisation of structural and surface speciation of representative commercially available cerium oxide nanoparticles

Environmental context.Manufactured nanoparticles, increasingly used in a wide range of products, can be released into the natural environment where they might pose a risk to environmental and human health. The nanoparticle characteristics that induce toxic effects, however, are not yet well-known. Understanding the toxicity and the fate and behaviour of nanoparticles in the environment requires precise characterisation of their properties at the nanoscale and the individual particle level. Abstract.The shape, morphology, crystallography, and oxidation state of commercially available cerium oxide nanoparticles as compared with bulk particles were studied by high-resolution transmission electron microscopy coupled to electron energy loss spectroscopy, along with scanning electron microscopy. Nano and bulk particles have the same crystalline structure and morphology as the fluorite-type structure with a mainly octahedral shape enclosed by eight {111} facets, or a truncated octahedral shape enclosed by eight {111} facets and two {002} facets, or eight {111} and two {002} and four {220} facets. Some defects, including twin boundaries and steps and kinks, were observed. Bulk ceria particles contain mainly CeIV, whereas ceria nanoparticles contain a large fraction of CeIII, which decreases after interaction with humic acid and biological media. These properties are likely to play an essential role in the environmental and toxicological behaviour of nanoparticles.

Monitoring of trace metals and pharmaceuticals as anthropogenic and socio-economic indicators of urban and industrial impact on surface waters.

The research focuses on the monitoring of trace metals and pharmaceuticals as potential anthropogenic indicators of industrial and urban influences on surface water. This study includes analysis of tracers use for the indication of water pollution events and discussion of the detection method of these chemicals. The following criteria were proposed for the evaluation of indicators: specificity (physical chemical properties), variability (spatial and temporal), and practicality (capacity of the sampling and analytical techniques). The combination of grab and passive water sampling (i.e., diffusive gradient in the thin film and polar organic chemical integrated samplers) procedure was applied for the determination of dissolved and labile trace metals (Ag, Cd, Cr, Cu, Ni, Pb, and Zn) and pharmaceuticals (carbamazepine, diazepam, paracetamol, caffeine, diclofenac, and ketoprofen). Samples were analyzed using inductively coupled plasma mass spectrometry (MS; trace metals) and liquid chromatography–tandem MS electrospray ionization+/− (pharmaceuticals). Our results demonstrate the distinctive spatial and temporal patterns of trace elements distribution along an urban watercourse. Accordingly, two general groups of trace metals have been discriminated: “stable” (Cd and Cr) and “time varying” (Cu, Zn, Ni, and Pb). The relationship Cd ≫ Cu > Ag > Cr ≥ Zn was proposed as an anthropogenic signature of the industrial and urban activities pressuring the environment from point sources (municipal wastewaters) and the group Pb–Ni was discussed as a relevant fingerprint of the economic activity (industry and transport) mainly from non-point sources (runoff, atmospheric depositions, etc.). Pharmaceuticals with contrasting hydro-chemical properties of molecules (water solubility, bioaccumulation, persistence during wastewater treatment processes) were discriminated on conservative, labile, and with combined properties in order to provide information on wastewater treatment plant efficiency, punctual events (e.g., accidents on sewage works, runoff), and uncontrolled discharges. Applying mass balance modeling, medicaments were described as relevant socio-economic indicators, which can give a picture of main social aspects of the region.

Effect of Basic Slag Addition on Soil Properties, Growth and Leaf Mineral Composition of Beans in a Cu-Contaminated Soil

Basic slag (BS) is an alkaline by-product of the steel industry with potential properties to ameliorate nutrient supply and metal stabilization in contaminated soils. The BS effects on soil pH, soil conductivity, growth and chemical composition of beans were investigated using an acid, sandy soil from a wood treatment facility containing 630 mg Cu kg−1. Pot experiments were carried out on a 2-week period with Phaseolus vulgaris L. An uncontaminated, sandy soil was used as a control (CTRL). BS was added into the soil (1 kg soil pot−1) to constitute four treatments in triplicates: 0% (T1), 1% (T2), 2% (T3), and 4% (T4) BS kg−1 air-dried soil. The BS addition increased soil pH, soil conductivity, and plant growth compared to the untreated soil. At 1% and 2% BS addition rate, highest shoot yields (dry weight, DW) occurred. Foliar Cu concentration varied from 5.6 mg kg−1 to 53.1 mg kg−1 in the following order: CTRL < T2, T3, T4 < T1. The highest decrease in the foliar Cu concentration, 2.3 times compared to T1 plants, was obtained for the T2 plants. The BS addition at 1% rate into the Cu-contaminated soil promoted bean growth with the lowest foliar Cu concentration. Foliar Ca concentration was enhanced in the T2, T3 and T4 treatments whereas the foliar P concentration was not promoted.

Characterization of the aquifers of the Bangui urban area, Central African Republic, as an alternative drinking water supply resource

Abstract This paper presents the results of a survey carried out in 2010 aimed at evaluating the type and quality of the groundwater resources of the Bangui region of the Central African Republic. This work is the first step towards the development of groundwater resources in the Central African Republic in order to find alternatives to direct pumping from the Ubangi River and provide the population of the suburbs with a safer drinking water supply from deep boreholes. By combining both geological and hydrogeochemical approaches, it appears that the geology of Bangui is favourable to the development of a secure and sustainable water supply from groundwater provided that the conditions of exploitation would be constrained by the local authorities. The deep Precambrian carbonate aquifers, known as the Bimbo and Fatima formations, are identified as target resources in view of the relatively good quality of their water from the chemical point of view, and the semi-confined structure of the aquifers that prevents the mixing with shallow aquifers that are already strongly affected by domestic and industrial pollution. The main difficulty in terms of exploitation is to appreciate the depth of the resource and the more or less fractured/palaeo-karstified type of the porosity. Editor Z.W. Kundzewicz Citation Djebebe-Ndjiguim, C.L., Huneau, F., Denis, A., Foto, E., Moloto-a-Kenguemba, G., Celle-Jeanton, H., Garel, E., Jaunat, J., Mabingui, J., and Le Coustumer, P., 2013. Characterization of the aquifers of the Bangui urban area, Central African Republic, as an alternative drinking water supply resource. Hydrological Sciences Journal, 58 (8), 1760–1778.

Origin and recharge mechanisms of groundwater in the upper part of the Awaj River (Syria) based on hydrochemistry and environmental isotope techniques

The Barada and Awaj basin is the most important and extensively used water basin in Syria. Chemical and isotopic data of groundwater have been used to determine the spatial distribution of hydrogeological features in the upper part of Awaj River catchment area located southwest of this basin. Hydrogeochemical evolution of groundwater reveals the domination of dissolution/precipitation mechanisms in these very complex stratigraphic sequences. The dissolution of carbonate rocks as well as reverse cation exchange processes seem to be the main factors controlling groundwater mineralization. The isotopic composition of precipitation and groundwater indicate that the modern-day atmospheric precipitation is the main source of groundwater recharge before an important evaporation occurred. The isotopic data also imply an existence of hydraulic connection between the different aquifers system. The results obtained allowed us to delineate two main spatial groundwater zones within the study area with different flow components. The south, central and eastern parts are considered to be one zone which is characterised by a shallow horizontal flow associated with active interaction between groundwater and hosting rocks. The nitrate concentrations in this zone are attributed to anthropogenic sources. The second zone consists in south-western, western and north-western parts where the karstic features are well developed mainly in the Jurassic strata. This zone is characterized by a high vulnerability to pollution confirmed by high values of nitrate coming from sewage water. The deep vertical groundwater flow component seems to be dominant in this zone and is controlled by fractures and geological structures.

Hydrochemistry to delineate groundwater flow conditions in the Mogher Al Mer area (Damascus Basin, Southwestern Syria)

The hydrochemistry of groundwater from the Mogher Al Mer area, located in southwestern Syria, has been used as a tool to identify and assess the hydrogeological systems and associated conditions. In this arid region of Syria, groundwater is considered as the main source of water supply for both drinking and irrigation purposes. The detailed description of hydrogeochemical conditions, including major ions, physico-chemical and in situ field parameters, has underlined the very complex variability of the stratigraphic sequences and hence the numerous hydrogeological units within the study area. On the one hand, groundwater chemical signature is found to be mainly controlled by the water–rock interaction processes in the mountainous western part of the study area. On the other hand, anthropogenic influences are observed in the eastern plain. In terms of recharge mechanisms, the region can be considered as a part of a main intermediate or even regional flow system instead of a local one.