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International audience; This paper presents an analysis, using process simulation, of the waste management system applied in a collection basin located in the south of Paris (France). The study was conducted in close cooperation with the "SYCTOM of Paris agglomeration", an operator in charge of managing 2.5 million tons/yr of municipal solid waste in the Paris area. The analysis includes a description of the current situation of waste management in this collection basin, the construction and calibration of a simulator that reproduces this situation, the simulation of scenarios that account for possible future changes in waste flows and treatment options and finally a comparison of scenario results. Results illustrate the interest of a process-based approach to waste management systems. Such an approach is complementary to life cycle analyses, which usually rely on more generic descriptions of waste treatment units. The detailed analysis of a waste management system using local data on waste streams and treatment units provides technical indicators of system efficiency expressed in terms of recycling rates, energy recovery, emission fluxes and costs. Such information can help reach a consensus with respect to the actual situation of waste management and provides decision-makers with quantitative arguments that can be brought into the public debate.

The study of atmospheric pollution by the aerosols includes scientific questions, resulting from both local (air quality, health impacts) and global (contaminant inputs into ecosystems, impact on global change) problems. The fine particles, especially PM2,5, represent a major objective for authorities, at the European scale, as well as at the French one, following the Grenelle Environment Forum. Their role as vectors of potentially toxic heavy metals (such as lead or cadmium) has only been studied since relatively recently. This article shows that the recent use of metal isotope systematics, mercury, cadmium and zinc, proves to be a reliable discrimination tool for tracking pollution sources of atmospheric particles. This will ultimately open the door for the application of these isotope systematics as tracers of sources of particulate atmospheric pollution., L'étude de la pollution atmosphérique par les aérosols intègre des questionnements scientifiques nés de problématiques à la fois locales (qualité de l'air, impacts sur la santé) et globales (apports de contaminants aux éco - systèmes, impact sur l'évolution du climat). Les particules fines, en particulier les PM2,5, constituent une priorité des pouvoirs publics, à l'échelle Européenne, ainsi qu'au niveau Français, à la suite du Grenelle de l'Environnement. Leur rôle en tant que vecteurs, entre autres, de métaux lourds potentiellement toxiques (tels que le plomb ou le cadmium) n'est étudié que depuis relativement peu de temps. Cet article montre que l'utilisation récente des isotopes de ces métaux, mercure, cadmium et zinc, s'avère un bon outil de discrimination des principaux pôles d'émission de particules. Ceci ouvre alors la porte pour leur application en tant qu'outils de traçage des sources de pollution atmosphérique particulaire