Groupement de Recherche Eau Sol Environnement, Université de Limoges, 123 avenue Albert Thomas, 87060 Limoges Cedex, France.
EDF-DPIH, Unité de Production Centre, 19 bis avenue de la Révolution, BP 406, 87012 Limoges Cedex, France.
Sci Total Environ. 2016 Mar 15;547:282-294. doi: 10.1016/j.scitotenv.2016.01.023. Epub 2016 Jan 12.
Sediments play an important role on the quality of aquatic ecosystems, notably in the reservoir areas where they can either be a sink or a source of contaminants, depending on the management and hydrological conditions. The physicochemical properties of 25 surface sediments samples of a reservoir catchment (Vaussaire, Cantal, France) were studied. Results show a strong influence of dam presence, notably on the grain size and organic matter (OM) contents. The concentrations of trace metals and metalloids (As, Cd, Cr, Cu, Ni, Pb and Zn) were also measured and compared with worldwide reservoir concentrations and international sediment quality guideline levels in order to assess the intensity of the metallic contamination. Cr and Ni are the trace elements presenting the significantly highest values at the catchment scale. Enrichment Factors (EF), calculated using both local and national backgrounds, show that metals have mainly a natural origin, explaining especially the Cr and Ni values, linked with the composition of parental rocks. Unexpectedly, all the observed metal concentrations are lower in the reservoir than upstream and downstream, which might be related to the high fresh OM inputs in the reservoir, diluting the global metallic contamination. Multivariate statistical analyses, carried out in order to identify the relationship between the studied metals and sediment characteristics, tend to support this hypothesis, confirming the unusually low influence of such poorly-degraded OM on trace element accumulation in the reservoir.
沉积物在水生态系统的质量中起着重要作用，特别是在水库地区，它们可能是污染物的汇或源，这取决于管理和水文条件。对一个水库流域（法国康塔尔省的沃萨尔）的 25 个表层沉积物样本的物理化学特性进行了研究。结果表明，大坝的存在有很强的影响，特别是对粒径和有机物（OM）含量的影响。还测量了痕量金属和类金属（As、Cd、Cr、Cu、Ni、Pb 和 Zn）的浓度，并与世界范围内水库的浓度和国际沉积物质量指导值进行了比较，以评估金属污染的强度。Cr 和 Ni 是痕量元素中在流域尺度上具有明显最高值的元素。使用本地和国家背景计算的富集因子（EF）表明，金属主要具有天然来源，这尤其解释了 Cr 和 Ni 的价值，这与母岩的组成有关。出乎意料的是，所有观察到的金属浓度在水库中都低于上下游，这可能与水库中高新鲜 OM 输入有关，稀释了全球金属污染。为了确定研究金属与沉积物特性之间的关系而进行的多变量统计分析，倾向于支持这一假设，证实了这种未充分降解的 OM 对水库中痕量元素积累的异常低影响。
