Université de Bordeaux, UMR 5805 EPOC, Av. des Facultés, 33405 Talence Cedex, France.
Chemosphere. 2011 Nov;85(8):1299-305. doi: 10.1016/j.chemosphere.2011.07.036. Epub 2011 Aug 24.
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 (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: ~0.3 mg kg(-1); Cd: ~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/Ag2) 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.
吉伦特河河口的水系受到历史金属污染（例如 Cd、Zn、Hg）的影响，几十年来，河口处的牡蛎（Crassostrea gigas）体内 Cd 浓度一直极高。基于最近的研究（Chiffoleau 等人，2005 年）揭示了吉伦特河牡蛎体内异常高的 Ag 浓度（高达 65mg/kg；干重），我们比较了长期（1955-2001 年）水库沉积物中 Ag 和 Cd 浓度与 1979 年至 2010 年期间采集的牡蛎中相应浓度的记录，以确定最近发现的 Ag 异常的来源和历史趋势。来自两个主要金属污染源上下游水库的沉积物岩芯提供了有关（i）地球化学背景（上游；Ag：约 0.3mg/kg；Cd：约 0.8mg/kg）和（ii）Ag 和 Cd 污染历史趋势的信息。结果表明，Ag 和 Cd 的浓度-深度剖面平行，支持共同的来源和运输。自 1986 年以来，浓度逐渐降低（Cd：从 300 降至 11mg/kg；Ag：从 6.7 降至 0.43mg/kg）反映了德卡兹维尔盆地锌矿石处理的终止以及随后的补救行动。相应地，1988 年以后，牡蛎体内 Cd 浓度下降（从 109 降至 26mg/kg，干重（dw）），而 1993 年以后，Ag 生物积累量从 38 增加到 116mg/kg，dw。根据锌矿石处理终止前（1981-1985 年）采集的牡蛎中 Cd/Ag 比值（Cd/Ag~2），并假设牡蛎中几乎所有 Cd 都来自金属点源，我们估计了该源对牡蛎中 Ag 浓度的贡献。过去 30 年的演变清楚地表明，最近未解释的牡蛎中 Ag 浓度增加是由于其他来源（如摄影、电子和新兴的 Ag 应用/材料）的贡献增加（1999 年后超过 70%）。
