Field-portable X-Ray Spectrometry as Rapid Measurement Tool for Environmental Geochemical Investigations in Former Mining Areas: The Case of Kirki Mines (Greece)

International audienc

Followup procedure in time-domain F-statistic searches for continuous gravitational waves

Potentially interesting gravitational-wave candidates (outliers) from the blind all-sky searches have to be confirmed or rejected by studying their origin and precisely estimating their parameters. We present the design and first results for the followup procedure of the {\tt Polgraw} all-sky search pipeline: a coherent search for almost-monochromatic gravitational-wave signals in several-day long time segments using the $F$-statistic method followed by the coincidences between the candidate signals. Approximate parameters resulting in these two initial steps are improved in the final followup step, in which the signals from detectors are studied separately, together with the network combination of them, and the true parameters and signal-to-noise values are established.Comment: 4 pages, 4 figures, published in Proceedings of the Polish Astronomical Society, vol. 7, 37-40 (2018

Caractérisation sur site de matrices contaminées par des composés volatils : teneur totale et première estimation de la mobilité

International audienceThe urban sprawl, pushes to the regeneration of brownfield sites located nearby cities. These old industrial areas of degraded and abandoned land are found today in the heart of cities and their requalification becomes key factor of urban development (RESCUE, 2005).This leads to a need for characterizing the soil and its pollution. However today, the mobility has to be evaluate (transfer) and therefore the risks of damage to targets beyond the total amount of pollutant (definition of the source of pollution). In this study, the aim is to better assess the impact on human health considering soil gas and groundwater.The field devices often are less reliable than laboratory equipment; however they offer the opportunity to multiply analysis on site, significantly increasing the representativeness of the site characterization. The GC used (HAPSITE) allows on site compound identification at concentration from ppt to ppm depending on the compound and the matrix considered.The use of this portable GC has demonstrated its ability to obtain on-site an initial identification of compounds that are not included in the usual analytical packages. This allows to adapt on site the analyses to be performed (case of an incomplete history of the site).In the case of volatile compounds, quick analyses after the sampling, allow to limit the risk of losses.To evaluate the mobility toward the gas phase, first tests were carried out from soil and water, by varying the head space (volume of the medium relative to the degassing volume) and heating temperature. To evaluate the mobility toward the water phase, extractions with water and with methanol were performed.The first results are encouraging but it remains to consolidate the protocols to make them robust (usable and transferable to all soil types).This project has received financial support of ADEME.La politique d’étalement des villes, aujourd’hui remise en cause, pousse à la réhabilitation des friches industrielles implantées à proximité des villes. Ces anciennes zones d’activités industrielles aujourd’hui dégradées et abandonnées se retrouvent actuellement au cœur de centres villes et leurs requalifications et réintégrations deviennent des facteurs clés d’aménagement urbain (RESCUE, 2005).Cela amène à un besoin de caractérisation de la matrice sol et de son contenu en polluant. Cependant aujourd’hui au-delà de la teneur totale en polluant (définition de la source de pollution), c’est davantage sa mobilité que l’on souhaite évaluer (transfert) et par là les risques d’atteinte de cibles. L’objectif ici est de mieux évaluer l‘impact sur la santé humaine en considérant aussi les gaz du sol et les eaux souterraines.Les appareils de terrain ont souvent une fiabilité plus faible que les appareils de laboratoire, cependant ils offrent l’opportunité de multiplier les analyses sur site, ce qui augmente significativement la représentativité des caractérisations de sites. La GC utilisée (HAPSITE) permet d’identifier des composés situés dans un domaine allant du ppt au ppm selon les composés et les matrices considérés.L’utilisation de la GC portable a démontré sa capacité à obtenir sur site une première identification des composés en présence dont certains ne sont pas inclus dans les packs analytiques proposés par les laboratoires permettant ainsi de réajuster les analyses à réaliser (atout en cas d’un historique de site incomplet).Dans le cas des composés volatils, la mesure au plus près du prélèvement, permet en outre de s’affranchir des risques de pertes.Pour évaluer la mobilité vers la phase gaz, des premiers essais ont été réalisés depuis des matrices sol et eau, en faisant varier l’espace de tête disponible (volume de la matrice par rapport au volume de dégazage) et la température. Pour évaluer la mobilité vers la phase eau, des extractions à l’eau et avec du méthanol ont été réalisées.Les premiers résultats sont encourageants mais il reste à consolider les protocoles afin de les rendre robustes (utilisables et transférables à tous types de sols).Ce projet a bénéficié d’un soutien financier de l’ADEME

Regional distributon of mercury in sediments of the main rivers of French Guiana

International audienceUse of mercury (Hg) for gold-mining in French Guiana (up until 2006) as well as the presence of naturally high background levels in soils, has led to locally high concentrations in soils and sediments. The present study maps the levels of Hg concentrations in river sediments from five main rivers of French Guiana (Approuague River, Comté River, Mana River, Maroni River and Oyapock River) and their tributaries, covering more than 5 450 km of river with 1 211 sampling points. The maximum geological background Hg concentration, estimated from 241 non-gold-mined streams across French Guiana was 150 ng g-1. Significant differences were measured between the five main rivers as well as between all gold-mining and pristine areas, giving representative data of the Hg increase due to past gold-mining activities. These results give a unique large scale vision of Hg contamination in river sediments of French Guiana and provide fundamental data on Hg distribution in pristine and gold-mined areas

Characterization and mobility of arsenic and heavy metalsinsoils polluted by the destruction of arsenic-containingshells from the Great War

International audienceDestruction of chemical munitions from World War I has caused extensive local top soil contamination by arsenic and heavy metals. The biogeochemical behavior of toxic elements is poorly documented in this type of environment. Four soils were sampled presenting different levels of contamination. The range of As concentrations in the samples was 1937–72,820 mg/kg. Concentrations of Zn, Cu and Pb reached 90,190 mg/kg, 9113 mg/kg and 5777 mg/kg, respectively. The high clay content of the subsoil and large amounts of charcoal from the use of firewood during the burning process constitute an ample reservoir of metals and As-binding materials. However, SEM–EDS observations showed different forms of association for metals and As. In metal-rich grains, several phases were identified: crystalline phases, where arsenate secondary minerals were detected, and an amorphous phase rich in Fe, Zn, Cu, and As. The secondary arsenate minerals, identified by XRD, were adamite and olivenite (zinc and copper arsenates, respectively) and two pharmacosiderites. The amorphous material was the principal carrier of As and metals in the central part of the site. This singular mineral assemblage probably resulted from the heat treatment of arsenic-containing shells. Microbial characterization included total cell counts, respiration, and determination of As(III)-oxidizing activities. Results showed the presence of microorganisms actively contributing to metabolism of carbon and arsenic, even in the most polluted soil, thereby influencing the fate of bioavailable As on the site. However, the mobility of As correlated mainly with the availability of iron sinks

Challenges in coupled on-line-on-mine-real time mineralogical and chemical analyses on drill cores

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 of coupling chemical and mineralogical analytical technologies to obtain most complete information on samples, (2) the effect of the sample surface state on the XRF and IR signals from portable instruments. The last point is crucial for combined instrumental on-line sensor design and the calibration of the different instruments, especially in the case of pXRF

Efficient long-term open-access data archiving in mining industries

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. 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 Framework (CIF, [1]) was developed and is maintained by the International Union of Crystallography (IUCr). This framework provides rich means for describing crystal structures and crystallographic experiments in an unambiguous, human- and machine- readable way, in a standard that is independent of the underlying data storage technology. The Crystallography Open Database (COD, [2]) has been successfully using the CIF framework to maintain its open-access crystallographic data collection for over a decade [3,4]. Since the CIF framework is extensible it is possible to use it for other branches of knowledge. The SOLSA system will generate data using different methods of material identification: XRF, XRD, Raman, IR and DRIFT spectroscopy. For XRD, the CIF is usable out-of-the-box, since we can rely on extensive data definition dictionaries (ontologies) developed by the IUCr and the crystallographic community. For spectroscopic techniques such dictionaries, to our best knowledge, do not exist; thus, the SOLSA team is developing CIF dictionaries for spectroscopic techniques to be used in the SOLSA expert system. All dictionaries will be published under liberal license and communities are encourage to join the development, reuse and extend the dictionaries where necessary. These dictionaries will enable access to open data generated by SOLSA by all interested parties. The use of the common CIF framework will ensure smooth data exchange among SOLSA partners and seamless data publication from the SOLSA project