What are the outcomes of an industrial remediation on a metal-impacted hydrosystem? A 2-year field biomonitoring of the filter-feeding bivalve Corbicula fluminea

• Published in: Chemosphere (Oxford) 2014-08, Vol.108, p.214-224
• Main Authors: Arini, A., Daffe, G., Gonzalez, P., Feurtet-Mazel, A., Baudrimont, M.
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Animals; Applied ecology; Applied sciences; Biological and medical sciences; Cadmium - analysis; Corbicula - chemistry; Corbicula - metabolism; Corbicula fluminea; Ecotoxicology, biological effects of pollution; Environmental Monitoring; Environmental Restoration and Remediation; Environmental Sciences; Exact sciences and technology; France; Fresh Water - chemistry; Fresh water environment; Fundamental and applied biological sciences. Psychology; Gene expression; Global environmental pollution; Metallothionein - genetics; Metallothionein - metabolism; Metallothioneins; Mining; Pollution; Recovery, metals; Remediation; Spectrophotometry, Atomic; Water Pollutants, Chemical - analysis; Zinc - analysis
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2014.01.042

•Since 2007 a remediation process was initiated on a mining site contaminated by metals (Cd and Zn).•Bivalves were exposed for two years to observe early remediation impacts on hydrosystem.•Metal concentrations in river and bivalves remained very high in organisms exposed downstream.•Bivalves were still sharply genetically impacted by metal contamination.•Recovery of aquatic communities after remediation can only be expected in the long term. The Riou-Mort watershed (southwest France) exhibits high metal contaminations (Cd and Zn) related to an important mining past. In this context, a remediation process has been implemented in 2007 to reduce the watershed contamination. The aim of this study was to assess the early effectiveness of the remediation process on the hydrosystem contamination state. A biomonitoring was realized over two years (2008–2010) with the filter-feeding bivalve Corbicula fluminea, exposed along a contamination gradient. Several biological parameters were monitored: (1) Cd and Zn bioaccumulation, (2) Metallothionein (MT) production as detoxification mechanism, (3) differential gene expression (cat, sod, gst, 12S, cox1, mt). The physicochemical data highlighted strong metal contamination persistence in the river water and failed to demonstrate a significant decrease of metal contamination during the 2-year monitoring. The bioaccumulation results confirmed the persistence of a water contamination despite remediation works, with maximum values measured downstream from the industrial site (Joany). The bioaccumulation increased in 2010, reaching 69.3±5.3μgCdg−1 DW at Joany in July 2010, whereas it did not exceed 1.4±0.2μgCdg−1 DW at the reference site throughout the biomonitoring. MT concentrations were closely related to the contamination gradient, especially at Joany, demonstrating their strong involvement in the detoxification processes. The mt gene induction was strongly correlated to the MT and metal concentrations. The gene inductions of cat, sod, gst and 12S were correlated to both the metal concentrations and the seasonal variations, especially temperatures. This suggests that environmental factors require serious consideration for the interpretation of bioaccumulation kinetics and thus for the assessment of the remediation effectiveness. Consequently, the whole results did not yet highlight strong beneficial effects of remediation work on the hydrosystem contamination state. First benefits of that process should be progressively fe