Le traçage anonyme, dangereux oxymore: Analyse de risques à destination des non-spécialistes

Dans le but affiché de ralentir la progression de l'épidémie COVID-19, la France envisage de mettre en place un système de traçage des contacts des maladesà l'aide d'une application mobile. Les concepteurs de ce type d'applications assurent qu'elles sont respectueuses de la vie privée. Cependant cette notion reste vague. Nous souhaitons donc contribuer au débat public en apportant unéclairage sur ce que pourrait et ne pourrait pas garantir une application de traçage, afin que chacun puisse se forger une opinion sur l'opportunité de son déploiement

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

Atmospheric trace element concentrations in total suspended particles near Paris, France

International audienceTo evaluate today’s trace element atmospheric concentrations in large urban areas, an atmospheric survey was carried out for 18 months, from March 2002 to September 2003, in Saclay, nearby Paris. The total suspended particulate matter (TSP) was collected continuously on quartz fibre filters. The TSP contents were determined for 36 elements (including Ag, Bi, Mo and Sb) using two analytical methods: Instrumental Neutron Activation Analysis (INAA) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The measured concentrations were in agreement within the uncertainties with the certified values for the polycarbonate reference material filter SRM-2783 (National Institute for Standard Technology NIST, USA). The measured concentrations were significantly lower than the recommended atmospheric concentrations. In 2003, the Pb atmospheric level at Saclay was 15 ng/m3, compared to the 500 ng/m3 guideline level and to the 200 ng/m3 observed value in 1994. The typical urban background TSP values of 1–2, 0.2–1, 4–6, 10–30 and 3–5 ng/m3 for As, Co, Cr, Cu and Sb, respectively, were inferred from this study and were compared with the literature data. The typical urban background TSP concentrations could not be realised for Cd, Pb and Zn, since these air concentrations are highly influenced by local features. The Zn concentrations and Zn/Pb ratio observed in Saclay represented a characteristic fingerprint of the exceptionally large extent of zinc-made roofs in Paris and its suburbs. The traffic-related origin of Ba, Cr, Cu, Pb and Sb was demonstrated, while the atmospheric source(s) of Ag was not identified

Seasonal variations of atmospheric CO 2 in the southern Indian Ocean

International audienceAtmospheric C0 1 recording at Amsterdam Island shows a 0. 7 ppm seasonal effect, non• attributable to local causes and significantly different from the results obtained in other southern hemisphere stations. An attempt is made at comparing this seasonal variation to C0 1 models

The 1982-1983 El Nino: a 6 billion ton COz release

International audienceThe atmospheric COz concentration at Amsterdam Island showed important variations of the increase rate during the 1982-1983 El Nitio. After elimination of the weak local and regional interferences, the main feature of the C 0 2 record is a slower than normal increase rate at the beginning and at the end of this El NiAo, i.e

Variation of the chemical composition of marine aerosols in a high biological productivity area

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Sulfate enrichment in marine aerosols owing to biogenic gaseous sulfur compounds

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Reevaluation of the role of dimethyl sulphide in the sulphur budget

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Assimilation of ammonium and nitrate nitrogen by bean plant

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