EDTA在植物修复复合污染河道疏浚底泥中的调控作用

Roles of EDTA on Phytoremediation of Combined Contamination in Dredged Sewage River Sediment

通过温室盆栽试验,在黑麦草修复重金属(Zn,Pb,Cu,Cd,Ni)-有机物复合污染的城市排污河道疏浚底泥的过程中投加3mmol.kg-1EDTA(分1次、2次、3次投加),研究了对黑麦草生长及重金属积累、底泥特性和TOC的影响.结果表明,投加EDTA:①增加了黑麦草体内积累的重金属数量,其中分3次投加的效果最为显著,Pb,Zn,Cu,Ni,Cd在地上部分的积累量分别较对照增加了2.74、1.99、1.59、1.55和7.78倍;分3次投加明显降低了黑麦草的叶绿素含量,1次投加叶绿素含量没有明显变化.②对底泥的pH没有明显的影响,但显著增加了底泥中NH4OAc提取态和DTPA提取态的重金属量.③底泥大颗粒体积百分比变大;其中分3次投加底泥颗粒体均粒径增大、比表面积减小、晶格强度减小,有助于底泥颗粒释放吸附的重金属.④提高了底泥中微生物的数量,其中分2次、3次投加,微生物数量是对照试验的1.33和1.47倍;明显降低了底泥的脲酶活性,但对过氧化氢酶活性的影响不明显.⑤增加了底泥的TOC含量.

Pot experiments were conducted to study the roles of EDTA in phytoremediation of heavy metal-organic contaminated dredged sewage river sediment by Lolium multiflorum L. 3mmol·kg^-1 EDTA was added to sediment through three manners （once, twice and three times, respectively）. The results showed that： with adding EDTA to the sediment （1）The accumulation amount of heavy metals to Lolium multiflorum L. increased, especially by added EDTA three times. Compared with the control, the accumulation of Pb, Zn, Cu, Ni, CA in shoots increased 2.74,1.99,1.59,1.55 and 7.78 times by added EDTA three times. The net increment was 32.33 mg·kg^-1, 1 393.56 mg·kg^-1, 64.42 mg·kg^-1, 36.57 mg·kg^-1 and 10.33 mg·kg^-1, respectively. Furthermore, the concentration of chlorophyll decreased by 42 % with 3 times EDTA addition, while the concentration of chlorophyll has no significant change with once EDTA addition, （2）pH hasn＇t much change, while NH4OAc and DTPA extractable heavy metal amount from sediment increased significantly. （3）The bulk percentage of big particle sediment increased. By added EDTA three times to sediment, the average particle size of sediment increased, while specific surface area and crystal lattice intensity decreased, which were contributed to the desorption of heavy metal from sediment particle. （4）Compared with the control, the amount of microorganism in sediment was increased 1.33 times and 1.47 times with adding EDTA twice and three times. The urease activity decreased, while the catalase activity hasn＇t much change. （5）TOC content was increased.