Seagrass species have been recommended as biomonitors of environmental condition and as tools for phytoremediation, due to their ability to concentrate anthropogenic chemicals. This study aims to provide novel information on metal accumulation in seagrasses under laboratory conditions to support their use as a tool in the evaluation and abatement of contamination in the field. We investigated the kinetics of cadmium uptake into adult leaf blades, leaf sheaths, rhizomes and roots of Cymodocea nodosa in exposure concentrations within the range of cadmium levels in industrial wastewater (0.5–40 mg L−1). A Michaelis–Menten-type equation satisfactorily described cadmium accumulation kinetics in seagrass parts, particularly at 0.5–5 or 10 mg L−1. However, an S equation best described the uptake kinetics in rhizomes at 5 mg L−1 and roots at 10 and 20 mg L−1. Equilibrium concentration and uptake rate tended to increase with the exposure concentration, indicating that seagrass displays a remarkable accumulation capacity of cadmium and reflect high cadmium levels in the surrounding medium. Concerning leaf blades and rhizomes, the bioconcentration factor at equilibrium (range 73.3–404.3 and 14.3–86.3, respectively) was generally lower at higher exposure concentrations, indicating a gradual reduction of available binding sites. Leaf blades and roots accumulated more cadmium with higher rate than sheaths and rhizomes. Uptake kinetics in leaf blades displayed a better fit to the Michaelis–Menten-type equation than those in the remaining plant parts, particularly at 0.5–10 mg L−1. A marked variation in tissue concentrations mainly after the steady state was observed at 20 and 40 mg L−1, indicative of the stress induced on seagrass cells. The maximum concentrations observed in seagrass parts at 5 and 10 mg L−1 were comparatively higher than those previously reported for other seagrasses incubated to similar exposure concentrations. Cymodocea nodosa displays a remarkable cadmium accumulation capacity and reflects high cadmium levels in the surrounding medium. Kinetic models satisfactorily describe cadmium uptake in seagrass parts, primarily in adult leaf blades, at high exposure concentrations, permitting to predict cadmium accumulation in field situations. Cymodocea nodosa appeared to be a valuable tool in the evaluation and abatement of cadmium contamination in coastal areas.

中文翻译：

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高暴露浓度下部分海草Cymodocea nodosa对镉的吸收动力学

由于海草物种能够浓缩人为化学物质，因此已被推荐作为环境状况的生物监测器和植物修复工具。这项研究旨在提供有关在实验室条件下海草中金属积累的新颖信息，以支持将其用作评估和消除野外污染的工具。我们研究了工业废水中镉浓度（0.5–40 mg L-1）的暴露浓度下，成年叶片，根鞘和根结线虫对镉的吸收动力学。Michaelis–Menten型方程式令人满意地描述了海草部分中镉的累积动力学，尤其是在0.5–5或10 mg L-1时。然而，一个S方程最能描述根茎在5 mg L-1和根在10和20 mg L-1时的吸收动力学。平衡浓度和吸收率倾向于随着暴露浓度的增加而增加，这表明海草显示出了显着的镉积累能力，并反映了周围介质中的高镉水平。关于叶片和根茎，在较高的暴露浓度下，处于平衡状态的生物浓缩系数（分别为73.3–404.3和14.3–86.3）通常较低，表明可用的结合位点逐渐减少。叶片和根部比叶片和根状茎累积更多的镉。叶片的吸收动力学表现出比其余植物部分更好的拟合Michaelis–Menten型方程，特别是在0.5–10 mg L-1时。在浓度为20和40 mg L-1时，主要是在稳态后，组织浓度出现明显变化，这表明海藻细胞受到了压力。在5和10 mg L-1的海草部位观察到的最大浓度相对高于先前报道的其他海草在相似暴露浓度下孵育的最大浓度。结节藻显示出显着的镉积累能力，并反映了周围培养基中的高镉水平。动力学模型令人满意地描述了在高暴露浓度下海藻部分（主要是成年叶片中）对镉的吸收，从而可以预测田间情况下的镉积累。结节藻似乎是评估和减少沿海地区镉污染的有价值的工具。