Analytical, Environmental and Geo-Chemistry Department (AMGC), Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
Analytical, Environmental and Geo-Chemistry Department (AMGC), Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
Sci Total Environ. 2023 Jul 15;882:163604. doi: 10.1016/j.scitotenv.2023.163604. Epub 2023 Apr 20.
The geochemical behavior of metals in water and sediment was investigated in the tidal section of the Zenne River in Belgium. Twelve-hour sampling campaigns were performed in October 2013 and March 2021 at the mouth of the Zenne River, under dry and rainy weather conditions respectively. Water samples were collected every hour while the passive samplers of Diffusive Gradients in Thin-films (DGT) were deployed continuously during a tidal cycle. In addition, bottom sediments were sampled at the tidal station and water samples were taken upstream and downstream of that station to identify the metal sources. The highest concentrations of Fe, Mn, Pb, Cr, Ni and Zn appear at low tide, indicating the Zenner River as a main source. However, for Co, Cd and Cu, other sources including upstream transport may explain their behavior during a tidal cycle. Fe, Pb and Cr are essentially transported in the particulate phase (<10 % dissolved) while the other metals in the dissolved phase (20 to 90 %). Rainfall and wind gust events also play an important role in trace metal distribution, increasing sediment resuspension and metal desorption. A good agreement was found between the time-averaged dissolved and DGT-labile metal concentrations with the exception of Cu and Fe, which form strong organic Cu complexes and Fe colloids respectively. The sediments of the tidal Zenne are contaminated by trace metals, thus acting as a secondary pollution source to the river. The reductive dissolution of Mn and Fe oxyhydroxides and the release of associated trace metals are the main mobilization mechanisms. Knowledge of the upstream and downstream levels in the water column, the benthic fluxes, which are based on turbulent diffusion, and the partitioning between dissolved and particulate phases allow to explain the metal concentration variations during the tidal cycle.
在比利时的泽纳河潮汐段研究了金属在水和沉积物中的地球化学行为。分别于 2013 年 10 月和 2021 年 3 月在泽纳河口进行了为期 12 小时的采样活动，分别在干燥和雨天条件下进行。在潮汐周期内，每隔一小时采集水样，同时连续部署扩散梯度薄膜（DGT）的被动采样器。此外，在潮汐站采集底泥样本，并在该站上下游采集水样，以确定金属来源。Fe、Mn、Pb、Cr、Ni 和 Zn 的浓度在低潮时最高，表明泽纳河是主要来源。然而，对于 Co、Cd 和 Cu，其他来源包括上游运输可能解释了它们在潮汐周期中的行为。Fe、Pb 和 Cr 主要以颗粒相（<10%溶解）运输，而其他金属则以溶解相（20-90%）运输。降雨和阵风事件也对痕量金属分布起着重要作用，增加了底泥再悬浮和金属解吸。除了 Cu 和 Fe 之外，时间平均溶解态和 DGT 不稳定金属浓度之间存在很好的一致性，Cu 形成强有机 Cu 配合物，Fe 形成胶体。潮汐泽纳河的沉积物受到痕量金属的污染，因此成为河流的二次污染源。Mn 和 Fe 氢氧化物的还原溶解以及相关痕量金属的释放是主要的迁移机制。了解水柱中的上下游水平、基于湍流传质的底栖通量以及溶解相与颗粒相之间的分配情况，可以解释潮汐周期中金属浓度的变化。
