螯合剂对植物修复污染河道疏浚底泥的调控

Role of Chelator 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EDTA(1mmol/kg和3mmol/kg),柠檬酸(5mmol/kg和15mmol/kg),DTPA(1mmol/kg和3mmol/kg),研究了对黑麦草生长及重金属积累、底泥特性的影响。结果表明,5mmol/kg的柠檬酸提高了重金属在植物地上部分的积累量,但没有达到显著水平,增大柠檬酸的投加量阻碍了植物的生长、抑制了对重金属的吸收。3mmol/kg的EDTA和DTPA均能提高植物对重金属的积累量,但也降低了植物的叶绿素含量。5mmol/kg的柠檬酸降低了底泥的pH,但其它2种螯合剂对底泥的pH没有明显的影响。3种螯合剂均增加了底泥溶液中重金属的浓度;增大了底泥大颗粒体积百分比,降低了其比表面积和晶格强度,有助于底泥颗粒释放吸附的重金属;提高了底泥中微生物的数量;增加了底泥的TOC含量。5mmol/kg的柠檬酸提高了底泥脲酶的活性,但效果不显著,而其它2种螯合剂均明显降低了脲酶活性,3种螯合剂对过氧化氢酶活性的影响均不明显。

Pot experiments were conducted to study the role of EDTA （1 mmol/kg and 3 mmol/kg）, citric acid （5 mmol/kg and15 mmol/kg） metal-organic contaminated dredged and DTPA （1 mmol/kg and 3 mmol/kg） in phytoremediation of heavy sewage river sediment by Lolium multiflorum Lam. The results showed that the shoot accumulation amount of Lolium multiflorum Lam to heavy metal increased with adding 5 mmol/kg citric acid, but the resuh was not statistically different from the control. Increasing the adding amount of citric acid posed a severe phytotoxicity to Lolium multiflorum Lam by stunted growth and diminished uptake rates. With adding 3 mmol/kg EDTA and DTPA, the accumulation of Pb,Zn,Cu,Ni,Cd in shoots increased, while the concentration of chlorophyll decreased, pH of the sediment was decreased with adding 5 mmol/kg citric acid, while pH had little change with adding the other two chelators. With adding the three chelators, the bulk percentage of big particle sediment and the average particle size of sediment increased, while specific surface area and crystal lattice intensity decreased, which were contributed to the desorption of heavy metals from sediment particle; the amount of microorganism in sediment and the TOC content were increased; the catalase activity hasn＇t much change. Compared with the control, the urease activity increased with adding 5 mmol/kg citric acid, but the result hadn＇t attained remarkable level; the activity decreased with adding the other two chelators.