Solid state partitioning of trace metals in suspended particulate matter from a river system affected by smelting-waste drainage Ste ´phane Audry * , Ge ´rard Blanc, Jo ¨rg Scha ¨fer Universite ´ Bordeaux 1, UMR CNRS 5805 EPOC, Traceurs Ge ´ochimiques et Mine ´ralogiques (T. G. M.), Avenue des faculte ´s, 33405 Talence cedex France Received 6 December 2004; accepted 25 May 2005 Available online 24 June 2005 Abstract The partitioning of particulate trace metals was investigated during one year of monthly sampling of suspended particulate matter (SPM) at eight sites along the Lot–Garonne fluvial system, known for its polymetallic pollution. The chemical partitioning in five operationally defined fractions (exchangeable/carbonate, Fe/Mn oxides, organic matter/sulfides, acid soluble, residual) was determined using a multiple single extraction approach. This approach showed that Cd, Zn, Pb and Cu were mainly associated with acid soluble phases (84–95%, 65–88%, 61–82% and 55–80% of the respective total metal content), and therefore showed a high mean potential of mobilization and bioavailability. In the Riou-Mort River, draining the smelting-wastes, Zn, Cd and Mn showed high mobility as they were little associated with the residual fraction (1–2%) and mainly bound to the dexchangeableT fraction of SPM (60–80%), probably weakly adsorbed on amorphous freshly-precipitated sulfide and/or oxide phases. Upstream and downstream of the anthropogenic source of metallic pollution, Mn and Cd, and Zn to a lesser extent, remained highly reactive. The other trace metals were mainly associated with the residual fraction and thus less mobile. However, the multiple single extraction scheme revealed that the most reactive transport phases were non-selectively extracted by the conventional extractants used here. These selectivity problems could not have been observed if sequential extraction was used. D 2005 Elsevier B.V. All rights reserved. Keywords: Selective extractions; Partitioning; Trace metals; Pollution; River; Suspended matter 1. Introduction Drainage of mining and smelting wastes is a seri- ous threat for fluvial systems as it results in massive input of dissolved and particulate trace metals into the aquatic environment (e.g., Gala `n et al., 2003; Lacal et al., 2003; Audry et al., 2004a). Although such wastes mainly affect relatively small areas near the source, dispersion and bioaccumulation of trace metals can occur over hundreds of kilometers in relatively short times (Salomons, 1995; Hochella et al., 1999; Bau- drimont et al., in press). Release of trace metals from 0048-9697/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.scitotenv.2005.05.035 * Corresponding author. Tel.: +33 540008834. E-mail addresses: s.audry@epoc.u-bordeaux1.fr (S. Audry), blanc@epoc.u-bordeaux1.fr (G. Blanc). Science of the Total Environment 363 (2006) 216– 236 www.elsevier.com/locate/scitotenv