Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA.
Chemosphere. 2011 Jun;83(11):1539-45. doi: 10.1016/j.chemosphere.2011.01.035. Epub 2011 Feb 8.
In addition to increasing the mobility of metal ions in the soil solution, chelating agents such as EDTA have been reported to alter both the total metal accumulated by plants and its distribution within the plant structures. Here, mature Mini-Sun Hybrid dwarf sunflowers exposed to 300 μM Cd(2+) in hydroponic solution had initial translocation rates of at least 0.12 mmol kg(-1)h(-1) and reached leaf saturation levels within a day when a 3-fold molar excess of EDTA was used. EDTA also promoted cadmium transfer from roots to the shoots. A threefold excess of EDTA increased the translocation factor (TF) 100-fold, resulting in cadmium levels in the leaves of 580 μg g(-1) and extracting 1400 μg plant(-1). When plants were exposed to dissolved cadmium without EDTA, the vast majority of the metal remained bound to the exterior of the root. The initial accumulation could be successfully modeled with a standard biosorption pseudo second-order kinetic equation. Initial accumulation rates ranged from 0.0359 to 0.262 mg g(-1)min(-1). The cadmium binding could be cycled, and did not show evidence of saturation under the experimental conditions employed, suggesting it might be a viable biosorbant for aqueous cadmium.
除了增加土壤溶液中金属离子的迁移性外，螯合剂如 EDTA 已被报道会改变植物积累的总金属量及其在植物结构内的分布。在这里，成熟的 Mini-Sun Hybrid 矮向日葵在水培溶液中暴露于 300 μM Cd(2+)，当使用 EDTA 的 3 倍摩尔过量时，初始迁移率至少为 0.12 mmol kg(-1)h(-1)，并在一天内达到叶片饱和水平。EDTA 还促进了镉从根部向地上部的转移。EDTA 的三倍过量将迁移因子 (TF) 增加了 100 倍，导致叶片中的镉含量达到 580 μg g(-1)，并提取了 1400 μg 植物(-1)。当植物暴露于没有 EDTA 的溶解镉时，大部分金属仍与根的外部结合。最初的积累可以用标准的生物吸附拟二级动力学方程成功模拟。初始积累速率范围从 0.0359 到 0.262 mg g(-1)min(-1)。镉的结合可以循环进行，并且在实验条件下没有显示出饱和的证据，这表明它可能是一种可行的水相中镉的生物吸附剂。
