valerie LAPERCHE - Academia.edu (original) (raw)

Papers by valerie LAPERCHE

Science of The Total Environment, Apr 1, 2018

HAL (Le Centre pour la Communication Scientifique Directe), Mar 14, 2017

HAL (Le Centre pour la Communication Scientifique Directe), Apr 3, 2019

Efficient data collection, analysis and preservation are needed to accomplish adequate business d... more Efficient data collection, analysis and preservation are needed to accomplish adequate business decision making. Long-lasting and sustainable business operations, such as mining, add extra requirements to this process: data must be reliably preserved over periods that are longer than that of a typical software life-cycle. These concerns are of special importance for the combined on-line-on-mine-real-time expert system SOLSA (http://www.solsa-mining.eu/) that will produce data not only for immediate industrial utilization, but also for the possible scientific reuse. We thus applied the experience of scientific data publishing to provide efficient, reliable, long term archival data storage. REAL TIME MINING Conference on Innovation on Raw Material Extraction Amsterdam 2017 142 Crystallography, a field covering one of the methods used in the SOLSA expert system, has long traditions of archiving and disseminating crystallographic data. To that end, the Crystallographic Interchange Frame...

Mining sites are usually sources of metal pollution many years after closure. Specific geo-chemic... more Mining sites are usually sources of metal pollution many years after closure. Specific geo-chemical phenomena such as acid drainage contribute to an increase of environmental impacts, especially if remediation measures were not taken at the time of mine closure (Bird et al., 2005). When a site is left exposed to the elements , pollution may arise from unmanaged waste piles, mine runoff water and tailings. The implementation of a reliable monitoring system is required to assess risks for the exposed resources (groundwater, cultivated areas, urban settlements or littoral), until the site is remediated. Monitoring data are essential to design remediation works. The monitoring network is designed using water, sediment or soil quality data along time at the critical points of the pollution transfer model. Traditionally, such points are selected from a large number of sampling points and laboratory analyses (baseline data). This is both expensive and lengthy. IGME followed an alternative ...

Arsenic (As) pollution in soils is a major health and environmental threat to water resources. Ar... more Arsenic (As) pollution in soils is a major health and environmental threat to water resources. Arsenic bioavailability in the environment is directly influenced by communities of As(III) oxidizing and As(V) reducing bacteria that catalyse the transformation of As(III) to As(V), a form easily precipitated, and the transformation of As(V) into As(III), the more mobile and toxic form, respectively. The objective of our work is to define molecular bio-indicators of arsenic mobility, in parallel with existing physic-chemical methods, and to evaluate their ability to predict As behaviour in the environment. Incubations of two soil samples from an industrial waste land containing different amounts of As (about 500 and 1600 ppm) showed that in aerobic conditions, favorable to As(III) oxidation, the microbial community stabilizes the arsenic by maintaining it as As(V). In anaerobic conditions, with the addition of a source of exogenic carbon to stimulate heterotrophic bacteria, the decrease ...

Previous studies have shown that lead interactions with hydroxylapatite induced hydroxypyromorphi... more Previous studies have shown that lead interactions with hydroxylapatite induced hydroxypyromorphite precipitation and thus can reduce Ph solubility. In the present study we investigated the solid-phase speciation of lead, immobilized by synthetic hydroxylapatite and natural fluoro- and chlorapatites. In order to understand the mechanisms of lead immobilization (precipitation of pyromorphite, etc), we studied the phosphates formed after reaction of aqueous lead with apatites or after co-precipitation of (Ph, Ca)-phosphates. These phosphates were analysed by different spectroscopic methods (XRD, IR, EXAFS and SEM) to determine the structure of the precipitated Pb-phosphates, and the mechanisms of formation of pyromorphite (OH{sup -}, F{sup -} and Cl{sup -}) as a function of pH, solid/solution ratio, and the reacting mineral and solution chemistry. The preliminary results showed that pure pyromorphite and not (Pb, Ca)-apatite was formed when we let aqueous lead react with apatite. (Pb,...

The SOLSA project aims to develop an innovative on-line-on-mine-real-time expert system, combinin... more The SOLSA project aims to develop an innovative on-line-on-mine-real-time expert system, combining sonic drilling, mineralogical and chemical characterization and data treatment. Ideally, this combination, highly demanded by mining and metallurgical companies, will speed up exploration, mining and processing. In order to evaluate the instrumental parameters for the SOLSA expert system, portable and laboratory analyses have been performed on four samples with contrasting lithologies: siliceous breccia, serpentinized harzburgite, sandstone and granite. More precisely, we evaluated the influence of the surface state of the sample on the signals obtained by portable X-Ray Fluorescence (pXRF) for chemistry and portable Infra-Red spectroscopy (pIR) for mineralogy. In addition, laboratory Raman spectroscopy, X-Ray Diffraction (XRD), XRF and ICP-OES laboratory analyses were performed to compare surface bulk mineralogical and chemical analyses. This presentation highlights (1) the importance...

La politique d’etalement des villes, aujourd’hui remise en cause, pousse a la rehabilitation des ... more La politique d’etalement des villes, aujourd’hui remise en cause, pousse a la rehabilitation des friches industrielles implantees a proximite des villes. Ces anciennes zones d’activites industrielles aujourd’hui degradees et abandonnees se retrouvent actuellement au cœur de centres villes et leurs requalifications et reintegrations deviennent des facteurs cles d’amenagement urbain (RESCUE, 2005). Cela amene a un besoin de caracterisation de la matrice sol et de son contenu en polluant. Cependant aujourd’hui au-dela de la teneur totale en polluant (definition de la source de pollution), c’est davantage sa mobilite que l’on souhaite evaluer (transfert) et par la les risques d’atteinte de cibles. L’objectif ici est de mieux evaluer l‘impact sur la sante humaine en considerant aussi les gaz du sol et les eaux souterraines. Les appareils de terrain ont souvent une fiabilite plus faible que les appareils de laboratoire, cependant ils offrent l’opportunite de multiplier les analyses sur si...

Environmental Science and Pollution Research, 2019

The Science of the total environment, Jan 31, 2016

Trace elements (TE) are indicative of industrial pollution in soils, but geochemical methods are ... more Trace elements (TE) are indicative of industrial pollution in soils, but geochemical methods are difficult to implement in contaminated sites with large numbers of samples. Therefore, measurement of soil magnetic susceptibility (MS) has been used to map TE pollutions, albeit with contrasted results in some cases. Effective radium concentration (ECRa), product of radium concentration by the emanation factor, can be measured in a cost-effective manner in the laboratory, and could then provide a useful addition. We evaluate this possibility using 186 topsoils sampled over about 783km(2) around two former lead and zinc smelters in Northern France. The ECRa values, obtained from 319 measurements, range from 0.70±0.06 to 12.53±0.49Bq·kg(-1), and are remarkably organized spatially, away from the smelters, in domains corresponding to geographical units. Lead-contaminated soils, with lead concentrations above 100mg·kg(-1) <3km from the smelters, are characterized on average by larger peak...

American Mineralogist, 2002

Although the use of mercury (Hg) for gold mining has been officially banned in French Guiana sinc... more Although the use of mercury (Hg) for gold mining has been officially banned in French Guiana since 2006, there are still reasons to be wary of its occurrence in river water and its impact on local populations. In fact, gold-mining generates intense soil erosion and high turbidity in the rivers downstream from mining sites. This contributes to Hg pollution and dissemination both via the remobilization of Hg naturally present in the soils and the release of metallic Hg from the gold recovery process. In the affected rivers, Hg transport and speciation is mainly controlled by the suspended particulate matter (SPM) rather than remaining dissolved. The aim of this study is to understand and quantify the fate of this SPM-associated Hg along the Boulanger river affected by old and new gold mining activities. Furthermore we provide recent data (2012) essential to evaluate the efficiency of legal gold mining companies in restoring and re-planting exploited zones to control erosion, river tur...

Spectrochimica Acta Part B: Atomic Spectroscopy, 2014

Journal of Contaminant Hydrology, 2015

Mercury (Hg) mobility and speciation in subsurface aquifers is directly linked to its surrounding... more Mercury (Hg) mobility and speciation in subsurface aquifers is directly linked to its surrounding geochemical and microbial environment. The role of bacteria on Hg speciation (i.e., methylation, demethylation and reduction) is well documented, however little data is available on their impact on Hg mobility. The aim of this study was to test if (i) Hg mobility is due to either direct iron oxide reduction by iron reducing bacteria (IRB) or indirect iron reduction by sulfide produced by sulfate reducing bacteria (SRB), and (ii) to investigate its subsequent fate and speciation. Experiments were carried out in an original column setup combining geochemical and microbiological approaches that mimic an aquifer including an interface of iron-rich and iron depleted zones. Two identical glass columns containing iron oxides spiked with Hg(II) were submitted to (i) direct iron reduction by IRB and (ii) to indirect iron reduction by sulfides produced by SRB. Results show that in both columns Hg was leached and methylated during the height of bacterial activity. In the column where IRB are dominant, Hg methylation and leaching from the column was directly correlated to bacterial iron reduction (i.e., Fe(II) release). In opposition, when SRB are dominant, produced sulfide induced indirect iron oxide reduction and rapid adsorption of leached Hg (or produced methylmercury) on neoformed iron sulfides (e.g., Mackinawite) or its precipitation as HgS. At the end of the SRB column experiment, when iron-oxide reduction was complete, filtered Hg and Fe concentrations increased at the outlet suggesting a leaching of Hg bound to FeS colloids that may be a dominant mechanism of Hg transport in aquifer environments. These experimental results highlight different biogeochemical mechanisms that can occur in stratified sub-surface aquifers where bacterial activities play a major role on Hg mobility and changes in speciation.