Quantitative Remote Sensing of African Dust Transport to the Mediterranean

International audienc

Arsenic speciation in shrimp and mussel from the Mid-Atlantic hydrothermal vents

cited By 52International audienceSpecimens of shrimp (Rimicaris exoculata) and mussel (Bathymodiolus puteoserpentis) were collected 3500 m below the ocean surface at the hydrothermal vents of the mid-Atlantic Ridge (TAG and Snake Pit sites, respectively). Arsenic, a potentially toxic element, is among the substances emitted by the hydrothermal vents. The hydrothermal vent shrimp, which are known to be a primary consumer of the primary producing chemolithoautotrophic bacteria, contained arsenic at 13 μg g-1 almost exclusively as arsenobetaine (AsB). Arsenic was present in the soft tissues of the mussel at 40 μg g-1 and the major part of the extractable arsenic species in the adductor muscle/mantle tissues and in the gill were present as dimethylarsinylriboside-derivatives (arsenosugars), while AsB was present at 16 and 3.6%, respectively, in these tissues. In spite of the absence of biosynthetically active algae, the pattern of arsenic species found in the shrimp and mussel species in the deep-sea is similar to that found in their counterparts from the ocean surface. It is concluded that the autotrophic bacteria of the hydrothermal vent ecosystem and the symbiotic bacteria harboured in the mussel species are responsible for the biosynthesis of the organoarsenicals detected in the two hydrothermal vent animal species. It is not known if the formation of the same organoarsenicals in the surface and deep sea ecosystems is primarily a detoxification process of inorganic arsenic, or whether these compounds play a physiological role

French National Alzheimer dataBank (BNA). The 2008-2012 French Alzheimer plan: description of the national Alzheimer information system.

International audienc

International system of units traceable results of Hg mass concentration at saturation in air from a newly developed measurement procedure

Data most commonly used at present to calibrate measurements of mercury vapor concentrations in air come from a relationship known as the “Dumarey equation”. It uses a fitting relationship to experimental results obtained nearly 30 years ago. The way these results relate to the international system of units (SI) is not known. This has caused difficulties for the specification and enforcement of limit values for mercury concentrations in air and in emissions to air as part of national or international legislation. Furthermore, there is a significant discrepancy (around 7% at room temperature) between the Dumarey data and data calculated from results of mercury vapor pressure measurements in the presence of only liquid mercury. As an attempt to solve some of these problems, a new measurement procedure is described for SI traceable results of gaseous Hg concentrations at saturation in milliliter samples of air. The aim was to propose a scheme as immune as possible to analytical biases. It was based on isotope dilution (ID) in the liquid phase with the 202Hg enriched certified reference material ERM-AE640 and measurements of the mercury isotope ratios in ID blends, subsequent to a cold vapor generation step, by inductively coupled plasma mass spectrometry. The process developed involved a combination of interconnected valves and syringes operated by computer controlled pumps and ensured continuity under closed circuit conditions from the air sampling stage onward. Quantitative trapping of the gaseous mercury in the liquid phase was achieved with 11.5 μM KMnO4 in 2% HNO3. Mass concentrations at saturation found from five measurements under room temperature conditions were significantly higher (5.8% on average) than data calculated from the Dumarey equation, but in agreement (−1.2% lower on average) with data based on mercury vapor pressure measurement results. Relative expanded combined uncertainties were estimated following a model based approach. They ranged from 2.2% to 2.8% (k = 2). The volume of air samples was traceable to the kilogram via weighing of water for the calibration of the sampling syringe. Procedural blanks represented on average less than 0.1% of the mass of Hg present in 7.4 cm3 of air, and correcting for these blanks was not an important source of uncertainty.JRC.D.2-Standards for Innovation and sustainable Developmen

Who should take responsibility for decisions on internationally recommended datasets? The case of the mass concentration of mercury in air at saturation

This discussion piece considers how decisions on internationally recommended datasets are made and implemented and, further, how the ownership of these decisions comes about. Examples are given of conventionally agreed data and values where the responsibility is clear and comes about through official designation or by common usage and practice over long time periods. The example of the dataset describing the mass concentration of mercury in air at saturation is discussed in detail. This is a case where there are now several competing datasets that are in disagreement with each other, some with historical authority and some more recent but, arguably, with more robust traceability to the SI. Further, it is elaborated that there is no body charged with the responsibility to make a decision on an international recommendation for such a dataset. This has led to the situation where several competing datasets are in use simultaneously. Close parallels are drawn with the current debate over changes to the ozone absorption cross section, which has equal importance to the measurement of ozone amount fraction in air and to subsequent compliance with air quality legislation. It is noted that in the case of the ozone cross section there is already a committee appointed to deliberate over any change. We make the proposal that a similar committee, formed under the auspices of IUPAC or the CIPM’s CCQM (if it adopted a reference data function) could be formed to perform a similar role for the mass concentration of mercury in air at saturation.JRC.D.3-Knowledge Transfer and Standards for Securit

Flow injection analysis as a tool for enhancing oceanographic nutrient measurements - A review

Macronutrient elements (C, N and P) and micronutrient elements (Fe, Co, Cu, Zn and Mn) are widely measured in their various physico-chemical forms in open ocean, shelf sea, coastal and estuarine waters. These measurements help to elucidate the biogeochemical cycling of these elements in marine waters and highlight the ecological and socio-economic importance of the oceans. Due to the dynamic nature of marine waters in terms of chemical, biological and physical processes, it is advantageous to make these measurements in situ and in this regard flow injection analysis (FIA) provides a suitable shipboard platform. This review therefore, discusses the role of FIA in the determination of macro- and micro-nutrient elements, with an emphasis on manifold design and detection strategies for the reliable shipboard determination of specific nutrient species. The application of various FIA manifolds to oceanographic nutrient determinations is discussed, with an emphasis on sensitivity, selectivity, high throughput analysis and suitability for underway analysis and depth profiles . Strategies for enhancing sensitivity and minimizing matrix effects, e.g. refractive index (schlieren) effects and the important role of uncertainty budgets in underpinning method validation and data quality are discussed in some detail.JRC.D.2-Standards for Innovation and sustainable Developmen