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Communication dans un congrès

Geochemical baseline of urban soils with undedicated datasets: link between methodology and environmental policies

Abstract : Geochemical baseline of urban soils with undedicated datasets: link between methodology and environmental policies B. Sauvaget (BRGM/Mines ParisTech PSL/ADEME), C. de Fouquet (Mines ParisTech PSL), C. Le Guern (BRGM), Hélène Roussel (ADEME) Optimized management of excavated soils in urban areas involves setting up channels for the reuse of unpolluted or slightly polluted soils, to limit landfill. In this frame, the French environmental policy proposes a methodology to verify the compatibility of these materials with the receiving site, as it is mentioned in the French guide on the management of excavated materials. This includes the geochemical background of soils. The usual algorithms used to calculate a geochemical baseline are adapted in case of dedicated datasets. However, France does not acquire such dedicated data in a systematic manner, as compared to other countries. Because the usual statistical approach shows important limits in case of undedicated datasets, we explore the potential of a spatial approach, and more particularly the potential of geostatistics. The available data coming mainly from pollution diagnostics, many values correspond to point source contamination. Because these data do not correspond to the geochemical background, there is a need to first separate the corresponding geochemical "anomalies" from the "background" values. These latter correspond to natural geochemistry of materials in place plus diffuse contamination due to human activities. To achieve this separation, we tested the potential of a filtering based on a factorial kriging. The geochemical data associate land use as well as geological descriptors. In this frame, we developed a R program. We examine its application at two different scales (a site and a district) and compare the results to previous statistical calculations. The results demonstrate that the factorial kriging can separate the geochemical anomalies based on their spatial variability, even with undedicated datasets. The comparison with the statistical threshold values shows that the range of values obtained with filtering better reflects the pedo-geochemical background by being certain not to take into account anomalies, even in cases of high proportions of these anomalies. It can be used at different scales. Such a geostatistical approach shows to be a good alternative to statistical algorithms for the calculation of the pedo-geochemical baseline. It allows also a spatial representation of the geochemical background and facilitates comparison between producing and receiving sites. This methodological work, carried out as part of a thesis funded by the French environmental Agency (Ademe) and BRGM, contributes to the reflection on the implementation of local geochemical quality standards for urban soils in France linked to the current French environmental policy.
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https://hal-brgm.archives-ouvertes.fr/hal-02049994
Contributeur : Cécile Le Guern Connectez-vous pour contacter le contributeur
Soumis le : mardi 18 janvier 2022 - 11:33:40
Dernière modification le : mercredi 3 août 2022 - 04:04:33

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  • HAL Id : hal-02049994, version 1

Citation

B. Sauvaget, C. De Fouquet, C. Le Guern, Hélène Roussel. Geochemical baseline of urban soils with undedicated datasets: link between methodology and environmental policies. AquaConSoil2019, May 2019, Antwerp, Belgium. ⟨hal-02049994⟩

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