Anthropophile elements in river sediments: Overview from the Seine River, FranceReport as inadecuate




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1 IPGP - Institut de Physique du Globe de Paris 2 State Key Laboratory of Environmental Geochemistry 3 IUF - Institut Universitaire de France

Abstract : In contrast to larger river systems that drain relatively pristine basins, little is known about the sediment geochemistry of rivers impacted by intense human activities. In this paper, we present a systematic investigation of the anthropogenic overprints on element geochemistry in sediments of the human-impacted Seine River, France. Most elements are fractionated by grain size, as shown by the comparison between suspended particulate matter SPM and riverbank deposits RBD. The RBD are particularly coarse and enriched in carbonates and heavy minerals and thus in elements such as Ba, Ca, Cr, Hf, Mg, Na, REEs, Sr, Ti, Th, and Zr. Although the enrichment-depletion pattern of some elements e.g., K, REEs, and Zr can largely be explained by a binary mixture between two sources, other elements such as Ag, Bi, Cr, Cd, Co, Cu, Fe, Mo, Ni, Pb, Sb, Sn, W, and Zn in SPM in Paris show that a third end-member having anthropogenic characteristics is needed to account for their enrichment at low water stage. These -anthropophile- elements, with high enrichment factors EFs relative to the upper continental crust UCC, display a progressive enrichment downstream and different geochemical behaviors with respect to the hydrodynamic conditions e.g., grain size compared to elements having mainly a natural origin. Our findings emphasize the need for systematic studies of these anthropophile elements in other human-impacted rivers using geochemical nor-malization techniques, and stress the importance of studying the chemical variability associated with hydro-dynamic conditions when characterizing riverine element geochemistry and assessing their flux to the ocean.





Author: Jiu-Bin Chen - Jérôme Gaillardet - Julien Bouchez - Pascale Louvat - Yi-Na Wang -

Source: https://hal.archives-ouvertes.fr/



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