Metal contamination budget at the river basin scale: a critical analysis based on the Seine River

International audienceMaterial flow analysis and environmental contamination analysis are merged into a flux-flow analysis (F2A) as illustrated for the metal circulation in the Seine River catchment. F2A combines about 30 metal flows in the anthroposphere (14 million people) and/or metal fluxes in the environment (atmosphere, soils, and aquatic system) originating from two dozens of sources. The nature and quality of data is very heterogeneous going from downscaled national economic statistics to upscaled daily environmental surveys. A triple integration is performed: space integration over the catchment (65000 km2), time integration for the 1950-2000 trend analysed at 5 year resolution, and a conceptual integration resulting in two F2A indicators. Despite the various data sources an average metal circulation is established for the 1994-2003 period and illustrated for zinc: (i) metal circulation in the anthroposphere is now two orders of magnitude higher than river outputs, (ii) long term metal storage, and their potential leaks, in soils, wastedumps and structures is also orders of magnitude higher than present river fluxes. Trend analysis is made through two F2A indicators, the per capita excess load at the river outlet and the leakage ratio (excess fluxes/metal demand). From 1950 to 2000, they both show a ten fold improvement of metal recycling while the metal demand has increased by 2.5 to 5 for Cd, Cu, Cr, Pb and Zn, and the population by 50%

Metal contamination budget at the river basin scale: an original Flux-Flow Analysis (F2A) for the Seine River

Material flow analysis and environmental contamination analysis are merged into a Flux-Flow analysis (F2A) as illustrated for the metal circulation in the Seine River catchment. F2A combines about 30 metal flows in the anthroposphere (14 million people) and/or metal fluxes in the environment (atmosphere, soils, and aquatic system) originating from two dozens of sources. The nature and quality of data is very heterogeneous going from downscaled national economic statistics to upscaled daily environmental surveys. <br><br> A triple integration is performed: space integration over the catchment (65 000 km<sup>2</sup>), time integration for the 1950–2000 trend analysed at 5 year resolution, and a conceptual integration resulting in two F2A indicators. <br><br> Despite the various data sources an average metal circulation is established for the 1994–2003 period and illustrated for zinc: (i) metal circulation in the anthroposphere is now two orders of magnitude higher than river outputs, (ii) long term metal storage, and their potential leaks, in soils, wastedumps and structures is also orders of magnitude higher than present river fluxes. Trend analysis is made through two F2A indicators, the per capita excess load at the river outlet and the leakage ratio (excess fluxes/metal demand). From 1950 to 2000, they both show a ten fold improvement of metal recycling while the metal demand has increased by 2.5 to 5 for Cd, Cu, Cr, Pb and Zn, and the population by 50%

Metal contamination budget at the river basin scale: an original Flux-Flow Analysis (F2A) for the Seine River

International audienc

Modeling fish communities for assessing past ecological status of watercourses

International audienceSince the last few decades, conservation of biodiversity emerged as an unavoidable societal expectation. As an example, the European Union, with the Water Framework directive (FWD), proposes to restore a good ecological status for river systems (mainly assessed on the basis of their biotas) in order to guarantee a balance and sustainable water use for human. The implementation of the WFD has set off numerous debates especially concerning the ways and targets considered for an efficient long term restoration of river ecosystems and their biological communities. Historical approaches are able to worthily light up such debates. By reconstructing trajectories of ecosystems on a long term perspective (i.e. several decades and centuries) it is possible to understand how human activities on watercourses and theirs catchments affected river ecosystems. Furthermore, they inform on the possible interaction between human impacts and much more uncontrolled influences linked to hydroclimatic fluctuations. Lastly they allow assessing if historical data on river biological communities, particularly those prior to the industrial revolution, could represent valuable references or targets for future rivers restoration planning. This paper focus on the Seine River basin in France, a catchment strongly and long standing impacted by human activities. The aim is to improve knowledge on the past ecological state of an aquatic ecosystem since the end of the 18th century, especially with a focus on fish communities. More precisely, the objective is to draw past fish communities' distribution under long term modifications of human pressures. Thus, we developed models predicting fish species distribution in the river network based on different environmental variables related to natural river features, climate and human activities. Coupling these models with a GIS we predict modifications of fish communities on the whole Seine River basin in a retrospective view point, considering changes of environmental conditions from the mid-18th century to nowadays. By comparing predictions with historical fish data, we assess capacity of our models to reconstruct past river ecosystems' trajectories and identify major human pressures driving these trajectories

Métropolisation et dégradation de la qualité des fleuves : quels constats pour quelles réponses ? Approche comparée de 1850 à 2010 de 4 métropoles Bruxelles, Berlin, Milan et Paris

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La construction politique de la commune mesure de la qualité des eaux superficielles en France : de l'équivalent-habitant au bon état (1959-2013)

International audiencePublic authorities in charge of preparing and implementing the 1964 French water law and the 2000 European Water framework Directive in 2000 similarly relied on inventories. In order to justify public action, they needed to objectify a situation which was either poorly known or informed by heterogeneous criteria. We show that political considerations are embedded in the indicators and the monitoring network of both inventories. They pertain to the type of realism which allows comparisons, shapes the frontiers of public policy, legitimates uses of water, and defines the sharing of the restoration's financial burden. We compare the controversies that rose during both inventories' construction to conclude on their political meaning.Lors de la préparation et la mise en ½uvre de la loi sur l'eau de 1964 et de la directive cadre européenne sur l'eau de 2000, les autorités publiques ont eu recours à des inventaires pour diagnostiquer une situation jusqu'alors mal connue ou mesurée selon des critères hétérogènes et pour justifier l'action publique choisie. Nous montrons que ces deux inventaires portent dans leurs indicateurs et leurs réseaux de surveillance des considérations politiques sur le type de réalisme justifiant les comparaisons possibles, le territoire pertinent pour l'action publique, les usages légitimes de l'eau et la répartition de l'effort environnemental. La comparaison des controverses qui ont jalonné leur construction permet de mettre en évidence deux projets politiques différents

La transaction comme régulation des déversements industriels en rivière, le cas de la Seine-et-Marne au XXe siècle

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