title: Persisting impact of historical mining activity to metal (Pb, Zn, Cd, Tl, Hg) and metalloid (As, Sb) enrichment in sediments of the Gardon River, Southern France.
abstract: In this study, we assessed past and present influence of ancient mining activity on metal(loid) enrichment in sediments of a former mining watershed (Gardon River, SE France), that is now industrialized and urbanized. A sedimentary archive and current sediments were characterized combining geochemical analyses, zinc isotopic analyses and sequential extractions. The archive was used to establish local geochemical background and recorded (i) increasing enrichment factors (EFs) for Pb, Zn, Cd, Tl, Hg, As and Sb throughout the industrial era, (ii) a contamination peak in 1976 attributed to a tailings dam failure, and (iii) current levels in 2002 and 2011 similar to those of 1969, except for Sb and Hg, reflecting a persisting contamination pattern. Inter-element relationships and spatial distribution of EF values of current sediments throughout the watershed suggested that both ancient and current contamination had a common origin for Pb, Zn, Cd, Tl and As related to the exploitation of Pb/Zn mineralization while old Sb mines and coal extraction area were the main sources for Sb and Hg respectively. This prevailing mining origin was reflected for Zn by a relatively uniform isotopic composition at δ(66)Zn=0.23 ± 0.03‰, although slight decrease from 0.23‰ to 0.18‰ was recorded from upstream to downstream sites along the river course in relation with the contribution of the lighter δ(66)Zn signature (~0.08‰) of acid mine drainage impacted tributaries. Results from sequential extractions revealed that the potential mobility of the studied metal(loid)s varied in the order Sb<Tl≈As<Zn<Pb<Cd, with an increase of the mobile pool for Cd, Pb, Zn and to a lesser extent for As and Tl associated to increased enrichment. Altogether, these results tend to demonstrate that ancient mining activity still contributes to metal enrichment in the sediments of the Gardon River and that some of these metals may be mobilized toward the water compartment.
authors.affiliation: HydroSciences UMR 5569, CNRS, Universités Montpellier I & II, IRD, Place Eugène Bataillon, CC MSE, 34095 Montpellier Cedex 5, France. Electronic address: eleonore.resongles@msem.univ-montp2.fr.
authors.forename: Eléonore
authors.initials: E
authors.lastname: Resongles
authors.affiliation: HydroSciences UMR 5569, CNRS, Universités Montpellier I & II, IRD, Place Eugène Bataillon, CC MSE, 34095 Montpellier Cedex 5, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Casiot
authors.affiliation: HydroSciences UMR 5569, CNRS, Universités Montpellier I & II, IRD, Place Eugène Bataillon, CC MSE, 34095 Montpellier Cedex 5, France.
authors.forename: Rémi
authors.initials: R
authors.lastname: Freydier
authors.affiliation: Géosciences UMR 5243, CNRS, Universités Montpellier II, Place Eugène Bataillon, CC 60, 34095 Montpellier Cedex 5, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Dezileau
authors.affiliation: Géosciences Environnement Toulouse UMR 5563, Université Paul Sabatier, CNRS, IRD, 14 Avenue Edouard Belin, 31400 Toulouse, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Viers
authors.affiliation: HydroSciences UMR 5569, CNRS, Universités Montpellier I & II, IRD, Place Eugène Bataillon, CC MSE, 34095 Montpellier Cedex 5, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Elbaz-Poulichet
mesh_terms: D000965:Antimony / Q000032:analysis; D001151:Arsenic / Q000032:analysis; D002104:Cadmium / Q000032:analysis; D004784:Environmental Monitoring; D005602:France; D019015:Geologic Sediments / Q000737:chemistry*; D007854:Lead / Q000032:analysis; D008628:Mercury / Q000032:analysis; D058955:Metalloids / Q000032:analysis*; D008670:Metals / Q000032:analysis*; D008906:Mining; D045483:Rivers / Q000737:chemistry; D013793:Thallium / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*; D015032:Zinc / Q000032:analysis
chemical_list: D058955:Metalloids; D008670:Metals; D014874:Water Pollutants, Chemical; D002104:Cadmium; D007854:Lead; D000965:Antimony; D013793:Thallium; D008628:Mercury; D015032:Zinc; D001151:Arsenic
keywords: Metal and metalloid; Mining-affected river; Sedimentary archive; Sequential extraction; Zinc isotopes