Long-term records of cadmium and silver contamination in sediments and oysters from the Gironde fluvial-estuarine continuum - Evidence of changing silver sources

Type Article
Date 2011-11
Language English
Author(s) Lanceleur Laurent1, Schafer Jörg1, Chiffoleau Jean-Francois2, Blanc Gerard1, Auger Dominique2, Renault Sophie3, Baudrimont Magalie3, Audry Stephane4
Affiliation(s) 1 : Univ Bordeaux, UMR EPOC 5805, F-33405 Talence, France.
2 : IFREMER, Ctr Nantes, Dept DCN BE, F-44311 Nantes 3, France.
3 : Univ Bordeaux, UMR EPOC 5805, F-33120 Arcachon, France.
4 : Univ Toulouse, UPS OMP, LMTG, F-31400 Toulouse, France.
Source Chemosphere (0045-6535) (Pergamon-elsevier Science Ltd), 2011-11 , Vol. 85 , N. 8 , P. 1299-1305
DOI 10.1016/j.chemosphere.2011.07.036
WOS© Times Cited 42
Keyword(s) Silver, Cadmium, Estuary, Oyster, Biomonitoring
Abstract The Gironde fluvial estuarine system is impacted by historic metal pollution (e.g. Cd, Zn, Hg) and oysters (Crassostrea gigas) from the estuary mouth have shown extremely high Cd concentrations for decades. Based on recent work (Chiffoleau et al., 2005) revealing anomalously high Ag concentrations (up to 65 mg kg(-1); dry weight) in Gironde oysters, we compared long-term (similar to 1955-2001) records of Ag and Cd concentrations in reservoir sediment with the respective concentrations in oysters collected between 1979 and 2010 to identify the origin and historical trend of the recently discovered Ag anomaly. Sediment cores from two reservoirs upstream and downstream from the main metal pollution source provided information on (i) geochemical background (upstream; Ag: similar to 0.3 mg kg(-1); Cd: similar to 0.8 mg kg(-1)) and (ii) historical trends in Ag and Cd pollution. The results showed parallel concentration-depth profiles of Ag and Cd supporting a common source and transport. Decreasing concentrations since 1986 (Cd: from 300 to 11 mg kg(-1); Ag: from 6.7 to 0.43 mg kg(-1)) reflected the termination of Zn ore treatment in the Decazeville basin followed by remediation actions. Accordingly, Cd concentrations in oysters decreased after 1988 (from 109 to 26 mg kg(-1), dry weight (dw)), while Ag bioaccumulation increased from 38 up to 116 mg kg(-1), dw after 1993. Based on the Cd/Ag ratio (Cd/Ag similar to 2) in oysters sampled before the termination of zinc ore treatment (1981-1985) and assuming that nearly all Cd in oysters originated from the metal point source, we estimated the respective contribution of Ag from this source to Ag concentrations in oysters. The evolution over the past 30 years clearly suggested that the recent, unexplained Ag concentrations in oysters are due to increasing contributions (> 70% after 1999) by other sources, such as photography, electronics and emerging Ag applications/materials. (C) 2011 Elsevier Ltd. All rights reserved.
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Lanceleur Laurent, Schafer Jörg, Chiffoleau Jean-Francois, Blanc Gerard, Auger Dominique, Renault Sophie, Baudrimont Magalie, Audry Stephane (2011). Long-term records of cadmium and silver contamination in sediments and oysters from the Gironde fluvial-estuarine continuum - Evidence of changing silver sources. Chemosphere, 85(8), 1299-1305. Publisher's official version : https://doi.org/10.1016/j.chemosphere.2011.07.036 , Open Access version : https://archimer.ifremer.fr/doc/00060/17109/