Impact of historical mining assessed in soils by kinetic extraction and lead isotopic ratios.
2014
Camizuli, Estelle | Monna, Fabrice | Bermond, A. | Manouchehri, N. | Besançon, S. | Losno, Rémi | van Oort, F. | Labanowski, J. | Perreira, A. | Chateau, Carmela | Alibert, Paul | Archéologie, Terre, Histoire, Sociétés [Dijon] (ARTeHiS) ; Ministère de la Culture et de la Communication (MCC)-Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS) | Environnement et Grandes Cultures (EGC) ; Institut National de la Recherche Agronomique (INRA)-AgroParisTech | Ingénierie Procédés Aliments (GENIAL) ; Institut National de la Recherche Agronomique (INRA)-AgroParisTech-Conservatoire National des Arts et Métiers [Cnam] (Cnam)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA) | AgroParisTech | Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)) ; Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS) | Physicochimie et Ecotoxicologie des SolS d'Agrosystèmes Contaminés (PESSAC) ; Institut National de la Recherche Agronomique (INRA) | Institut de chimie des milieux et matériaux de Poitiers [UMR 7285] (IC2MP [Poitiers]) ; Université de Poitiers = University of Poitiers (UP)-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS) | UFR Sciences de la Vie, de la Terre et de l'Environnement (Université de Bourgogne) (UFR SVTE) ; Université de Bourgogne (UB) | Biogéosciences [UMR 6282] (BGS) ; Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS) | Funds from the FEDER, the Regional Council of Burgundy, the University of Burgundy, Bibracte, the Morvan Regional Nature Park and the French Ministry of Research.
12 pages
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Afficher plus [+] Moins [-]anglais. The aim of this study is to estimate the long-term behaviour of trace metals, in two soils differently impacted by past mining. Topsoils from two 1 km(2) zones in the forested Morvan massif (France) were sampled to assess the spatial distribution of Cd, Cu, Pb and Zn. The first zone had been contaminated by historical mining. As expected, it exhibits higher trace-metal levels and greater spatial heterogeneity than the second non-contaminated zone, supposed to represent the local background. One soil profile from each zone was investigated in detail to estimate metal behaviour, and hence, bioavailability. Kinetic extractions were performed using EDTA on three samples: the A horizon from both soil profiles and the B horizon from the contaminated soil. For all three samples, kinetic extractions can be modelled by two first-order reactions. Similar kinetic behaviour was observed for all metals, but more metal was extracted from the contaminated A horizon than from the B horizon. More surprising is the general predominance of the residual fraction over the "labile" and "less labile" pools. Past anthropogenic inputs may have percolated over time through the soil profiles because of acidic pH conditions. Stable organo-metallic complexes may also have been formed over time, reducing metal availability. These processes are not mutually exclusive. After kinetic extraction, the lead isotopic compositions of the samples exhibited different signatures, related to contamination history and intrinsic soil parameters. However, no variation in lead signature was observed during the extraction experiment, demonstrating that the "labile" and "less labile" lead pools do not differ in terms of origin. Even if trace metals resulting from past mining and metallurgy persist in soils long after these activities have ceased, kinetic extractions suggest that metals, at least for these particular forest soils, do not represent a threat for biota.
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