柠檬酸对黑麦草修复铀污染土壤的影响

Effect of Citric Acid on Uranium Contaminated Soil Repaired by Lolium perenne

为探究柠檬酸浓度对黑麦草修复铀污染土壤的效率及其生理特性的影响,通过盆栽试验,研究了15mg/kg铀胁迫下不同浓度(0、1、5、10mmol/kg)柠檬酸对黑麦草生长、生理及重金属积累与分布的影响。结果表明:相同浓度铀胁迫下,随柠檬酸浓度的升高,黑麦草长势、光合色素、可溶性蛋白含量、根系活力、还原型谷胱甘肽(GSH)及几种酶(过氧化物酶(POD)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽还原酶(GR))的活性呈先升后降的趋势;黑麦草根叶质膜透性、丙二醛(MDA)含量及氧化型谷胱甘肽(GSSG)含量逐渐上升;黑麦草对铀的富集量呈先升后降的趋势,但均表现为根部富集量高于地上部分;亚细胞分布中,铀的富集量为细胞壁及残渣部分>可溶性部分>细胞器及膜部分,且各部分铀含量均先增后降。透射电镜结果显示,铀胁迫对黑麦草超微结构造成了不可逆伤害,添加5mmol/kg柠檬酸,损伤程度得以减轻。以上结果表明,低浓度(1、5mmol/kg)柠檬酸可促进黑麦草在铀污染土壤中的生长,增强黑麦草对铀污染土壤的修复效率,其中5mmol/kg柠檬酸的施加效果最佳,而10mmol/kg柠檬酸则会抑制黑麦草生长。

To explore the effects of citric acid concentration on the remediation of uranium contaminated soil by Lolium perenne and it＇s physiological characteristics,pot experiments were conducted to investigate the effects of different citric acid concentrations（0,1,5,10mmol/kg）on the growth,physiology and uranium accumulation anddistribution of Lolium perenne under the environment of 15mg/kg uranium stress.The results show that with the increase of citric acid concentrations,cell inclusion parameters including growth,photosynthetic pigments,soluble protein content,root vitality,and the activities of glutathione and several enzymes,in Lolium perenne firstly increase and then decrease.The membranous permeability,malondialdehyde contents and oxidised glutathione contents gradually increase.The uranium contents in various Lolium perenne positions firstly increase and then decrease,but the uranium contents in the root are much higher than those in the above-ground parts.The subcellular uranium distributions in cells show that the enrichment of uranium is cell wall and residue partsoluble partorganelles and membrane parts,and the enrichment of uranium firstly increases and then decreases under the same concentration of uranium.The electron microscopy images show that the environment of uranium stress can lead to irreversible damage on Lolium perenne ultrastructures,while the addition of 5mmol/kg citric acid can reduce the damage degree.It is concluded that citric acid with low concentrations of1 and 5mmol/kg can promote the growth and remediation efficiency of Lolium perenne in uranium contaminated soil.And 5mmol/kg citric acid can reach the best effect,while10mmol/kg can limit the growth of Lolium perenne.