Return of naturally sourced Pb to Atlantic surface waters

Anthropogenic emissions completely overwhelmed natural marine lead (Pb) sources during the past century, predominantly due to leaded petrol usage. Here, based on Pb isotope measurements, we reassess the importance of natural and anthropogenic Pb sources to the tropical North Atlantic following the nearly complete global cessation of leaded petrol use. Significant proportions of up to 30-50% of natural Pb, derived from mineral dust, are observed in Atlantic surface waters, reflecting the success of the global effort to reduce anthropogenic Pb emissions. The observation of mineral dust derived Pb in surface waters is governed by the elevated atmospheric mineral dust concentration of the North African dust plume and the dominance of dry deposition for the atmospheric aerosol flux to surface waters. Given these specific regional conditions, emissions from anthropogenic activities will remain the dominant global marine Pb source, even in the absence of leaded petrol combustion

Utilisations de procédés électrochimiques dans le traitement des effluents industriels

Les réactions électrochimiques sont employées dans des techniques séparatives dont les applications concernent la récupération, et la purification, de substances ioniques valorisables. Dans le cas de la concentration d'ions par électrodialyse, l'utilisation de séparateurs membranaires sélectifs permet, en même temps, de purifier les solutions concentrées obtenues, ce qui constitue un avantage par rapport aux autres techniques de concentration. L'utilisation de membranes bipolaires permet de produire des bases et des acides, à partir d'effluents salins, et donc de valoriser des sels dont le rejet dans l'environnement n'est pas souhaitable, et dont l'inertage avant stockage, sous forme solide, est rendu difficile par la grande solubilité de ces sels

Desert dust impacts on human health: an alarming worldwide reality and a need for studies in West Africa

High desert dust concentrations raise concerns about adverse health effects on human populations. Based on a systematic literature review, this paper aims to learn more about the relationship between desert dust and human health in the world and to analyse the place of West Africa as a study area of interest. Papers focussing on the potential relationship between dust and health and showing quantitative analyses, published between January 1999 and September 2011, were identified using the ISI Web of Knowledge database (N = 50). A number of adverse health effects, including respiratory, cardiovascular and cardiopulmonary diseases, are associated with dust. This survey highlights obvious dust impacts on human health independently of the study area, health outcomes and method. Moreover, it reveals an imbalance between the areas most exposed to dust and the areas most studied in terms of health effects. None of these studies has been conducted in West Africa, despite the proximity of the Sahara, which produces about half of the yearly global mineral dust. In view of the alarming results in many parts of the world (Asia, Europe, America), this paper concludes by stressing the importance of carrying out impact studies of Saharan dust in West Africa, where dust events are more frequent and intense than anywhere else