Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69518, Vaulx-en-Velin, France.
Université Savoie Mont-Blanc, UMR 42 CARRTEL, 73376, Le Bourget du Lac, France.
Environ Sci Pollut Res Int. 2019 May;26(14):14050-14058. doi: 10.1007/s11356-019-04729-7. Epub 2019 Mar 9.
Alterations in the timing, frequency, and magnitude of water level fluctuations (WLF) in lakes may result in important changes in abiotic parameters that can affect sediment-borne contaminant mobility at the sediment-water-biota interfaces in littoral zones. This study aims to assess the mobility of trace metals (TMs)-Cd, Cr, Cu, Ni, Pb, and Zn-under laboratory-simulated WLF (i.e., drying and reimmersion of sediments) through a three-pronged approach. One surficial sediment was sampled from the shoreline of a large French lake exhibiting an artificially limited WLF. A sample was enriched with a solution of TMs to ensure significant measurements of mobility. The spiked and naturally contaminated sediments were dried and reimmersed. The first approach consisted in measuring the mobility of TMs from the sediment to the water column under resuspensions of particles through leaching tests. The second approach assessed the partitioning of TMs between the different binding forms within the sediments through sequential extraction tests. The last approach tested the changes in TM bioconcentration in organisms exposed to sediment through microcosm assays. The hypothesis was that WLF may increase mobility from the sediment to the water column relative to mobility from the residual to easily mobilizable fractions within the sediments and consequently increase the bioconcentration of less inert trace metals, mostly Cd and Zn. This hypothesis was partly rejected as TM binding forms mainly increased toward the residual fractions within the sediment, especially for Cd and Zn, and bioconcentration mainly decreased following WLF. However, TM concentration increased in the water column when WLF included great resuspension of particles. The study also provides insights into the complex relationships among contaminant mobility to the water column, bioavailability, and bioconcentration, especially in the context of large abiotic disturbances such as WLF. These findings may be useful for further management strategies for WLF-regulated lakes and reservoirs.
湖泊水位波动（WLF）的时间、频率和幅度的变化可能导致非生物参数发生重要变化，从而影响滨岸带沉积物-水-生物界面上的沉积物中污染物的迁移。本研究旨在通过三管齐下的方法评估痕量金属（TMs）-Cd、Cr、Cu、Ni、Pb 和 Zn 在实验室模拟 WLF （即沉积物的干燥和再浸没）下的迁移性。从法国一个大型湖泊的滨岸线采集了一个表层沉积物，该湖泊的 WLF 受到人为限制。对一个样品进行了 TMs 溶液的富集处理，以确保对迁移性进行显著测量。对加标和自然污染的沉积物进行干燥和再浸没。第一种方法是通过浸出试验测量在颗粒再悬浮下，从沉积物到水相的 TM 迁移性。第二种方法是通过顺序提取试验评估 TMs 在沉积物中不同结合形态之间的分配。最后一种方法是通过微宇宙试验测试暴露于沉积物的生物体中 TM 的生物浓缩变化。假设是 WLF 可能会增加相对于沉积物中残留到易迁移分数的迁移性，从而增加较惰性痕量金属（主要是 Cd 和 Zn）的生物浓缩。该假设部分被否定，因为 TM 结合形态主要向沉积物中的残留分数增加，尤其是 Cd 和 Zn，并且 WLF 后生物浓缩主要降低。然而，当 WLF 包括大量颗粒再悬浮时，TM 浓度会增加到水柱中。该研究还为研究污染物向水柱的迁移性、生物可利用性和生物浓缩性之间的复杂关系提供了思路，特别是在 WLF 等大的非生物干扰情况下。这些发现可能对 WLF 调节的湖泊和水库的进一步管理策略有用。
