Contrasting isotopic signatures between anthropogenic and geogenic Zn and evidence for post-depositional fractionation processes in smelter-impacted soils from Northern France - Université Pierre et Marie Curie Accéder directement au contenu
Article Dans Une Revue Geochimica et Cosmochimica Acta Année : 2011

Contrasting isotopic signatures between anthropogenic and geogenic Zn and evidence for post-depositional fractionation processes in smelter-impacted soils from Northern France

Résumé

Zinc isotopes have been studied along two smelter-impacted soil profiles sampled near one of the largest Pb and Zn processing plants in Europe located in northern France, about 50 km south of Lille. Mean delta(66)Zn values along these two soil profiles range from +0.22 +/- 0.17 parts per thousand (2 sigma) to +0.34 +/- 0.17 parts per thousand (2 sigma) at the lowest horizons and from +0.38 +/- 0.45 parts per thousand (2 sigma) to +0.76 +/- 0.14 parts per thousand (2 sigma) near the surface. The delta(66)Zn values in the lowest horizons of the soils are interpreted as being representative of the local geochemical background (mean value +0.31 +/- 0.38 parts per thousand), whereas heavier delta(66)Zn values near the surface of the two soils are related to anthropogenic Zn. This anthropogenic Zn occurs in the form of franklinite (ZnFe(2)O(4))-bearing slag grains originating from processing wastes at the smelter site and exhibiting delta(66)Zn values of +0.81 +/- 0.20 parts per thousand (2 sigma). The presence of franklinite is indicated by EXAFS analysis of the topsoil samples from both soil profiles as well as by micro-XANES analysis of the surface horizon of a third smelter-impacted soil from a distant site. These results indicate that naturally occurring Zn and smelter-derived Zn exhibit significantly different delta(66)Zn values, which suggests that zinc isotopes can be used to distinguish between geogenic and anthropogenic sources of Zn in smelter-impacted soils. In addition to a possible influence of additional past sources of light Zn (likely Zn-sulfides and Zn-sulfates directly emitted by the smelter), the light delta(66)Zn values in the surface horizons compared to smelter-derived slag materials are interpreted as resulting mainly from fractionation processes associated with biotic and/or abiotic pedological processes (Zn-bearing mineral precipitation, Zn complexation by organic matter, and plant uptake of Zn). This conclusion emphasizes the need for additional Zn isotopic studies before being able to use Zn isotopes to trace sources and pathways of this element in surface environments

Dates et versions

hal-00659651 , version 1 (13-01-2012)

Identifiants

Citer

Farid Juillot, Chloe Marechal, Guillaume Morin, Delphine Jouvin, Sylvain Cacaly, et al.. Contrasting isotopic signatures between anthropogenic and geogenic Zn and evidence for post-depositional fractionation processes in smelter-impacted soils from Northern France. Geochimica et Cosmochimica Acta, 2011, 75 (9), pp.2295-2308. ⟨10.1016/j.gca.2011.02.004⟩. ⟨hal-00659651⟩
124 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More