Isotope Climatology and Environmental Research Centre (ICER), Institute for Nuclear Research, Hungarian Academy of Sciences, Bem tér 18/C, 4026, Debrecen, Hungary.
Department of Biology, University of Nyíregyháza, POBox 166, H-4401, Nyíregyháza, Hungary.
Water Res. 2018 May 15;135:104-111. doi: 10.1016/j.watres.2017.12.074. Epub 2017 Dec 30.
The use of gadolinium-based contrasting agents (GBCA) is increasing because of the intensive usage of these agents in magnetic resonance imaging (MRI). Waste-water treatment does not reduce anthropogenic Gd-concentration significantly. Anomalous Gd-concentration in surface waters have been reported worldwide. However, removal of GBCA-s by aquatic macrophytes has still hardly been investigated. Four aquatic plant species (Lemna gibba, Ceratophyllum demersum, Elodea nuttallii, E. canadensis) were investigated as potential biological filters for removal of commonly used but structurally different GBCA-s (Omniscan, Dotarem) from water. These plant species are known to accumulate heavy metals and are used for removing pollutants in constructed wetlands. The Gd uptake and release of the plants was examined under laboratory conditions. Concentration-dependent infiltration of Gd into the body of the macrophytes was measured, however significant bioaccumulation was not observed. The tissue concentration of Gd reached its maximum value between day one and four in L. gibba and C. demersum, respectively, and its volume was significantly higher in C. demersum than in L. gibba. In C. demersum, the open-chain ligand Omniscan causes two-times higher tissue Gd concentration than the macrocyclic ligand Dotarem. Gadolinium was released from Gd-treated duckweeds into the water as they were grown further in Gd-free nutrient solution. Tissue Gd concentration dropped by 50% in duckweed treated by Omniscan and by Dotarem within 1.9 and 2.9 days respectively. None of the macrophytes had a significant impact on the Gd concentration of water in low and medium concentration levels (1-256 μg L). Biofiltration of GBCA-s by common macrophytes could not be detected in our experiments. Therefore it seems that in constructed wetlands, aquatic plants are not able to reduce the concentration of GBCA-s in the water. Furthermore there is a low risk that these plants cause the accumulation of anthropogenic Gd in the food chain.
由于磁共振成像（MRI）中这些造影剂的大量使用，镧系元素基造影剂（GBCA）的使用正在增加。废水处理并不能显著降低人为 Gd 浓度。全世界都有报道称地表水中存在异常的 Gd 浓度。然而，水生植物对 GBCA 的去除作用仍鲜有研究。四种水生植物（浮萍、金鱼藻、水鳖、加拿大水芹）被作为潜在的生物滤器，用于去除水中常用但结构不同的 GBCA（欧乃影、多它醇）。这些植物被认为能积累重金属，并且被用于人工湿地中去除污染物。在实验室条件下，研究了这些植物对 Gd 的吸收和释放。测量了 Gd 在大型植物体内的浓度依赖性渗透，但未观察到明显的生物积累。在浮萍和金鱼藻中，Gd 的组织浓度分别在第 1 天和第 4 天达到最大值，并且在金鱼藻中的体积明显高于浮萍。在金鱼藻中，开链配体欧乃影导致的组织 Gd 浓度是大环配体多它醇的两倍。当浮萍在不含 Gd 的营养溶液中进一步生长时，Gd 处理过的浮萍会将 Gd 释放到水中。浮萍用欧乃影和多它醇处理后，组织 Gd 浓度分别在 1.9 和 2.9 天内下降了 50%。在低浓度和中浓度（1-256μg/L）水平下，没有一种大型植物对水中 Gd 浓度有显著影响。在我们的实验中，常见的大型植物对 GBCA 的生物过滤作用无法检测到。因此，在人工湿地中，水生植物似乎无法降低水中 GBCA 的浓度。此外，这些植物将人为 Gd 积累到食物链中的风险很低。
